Help with design + RFID

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Is there any design tips? I'm sure we can't design the entire RF portion - so we were looking into getting a kit - but what kind of kit can we use that will sense an RFID in a 20m radius and send the value stored on the chip and send that value to another circuit we have?

I'm thinking we'll be using alot of microelectronic design / embedded processors.

any more help?

snipped-for-privacy@gmail.com wrote in news:1186318877.519597.95650 @x40g2000prg.googlegroups.com:

Search for programmable RFID chips.

Then find RFID tags that use those chips, and the reader/programmer system used for them.

I think you're being optimistic if you think you can read a passive RFID tag within a 20m radius.

Indeed! The poster falls into the "dreamer" category.

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
         America: Land of the Free, Because of the Brave

I think he stated that he (they) are young engineers.

Practical matters sometimes get in the way of a "good" design.

Experience and testing are missing in an 12 week class.

donald

At least he admitted they are students.

If we were to design a prototype with a range of a 1 - 1.5 meters - would passive RFID still be viable. Also - where can we get help with designing circuits with RFID modules?

Again we're third ELECTRICAL ENGINEERING students with no prior of knowledge of RFID.

NO

NO

For third years students, you still need to learn to do your own research and testing.

Passive RFID is only good for an inch or two.

On a good day.

If your lucky.

If your antenna is as large as a door.

Good luck

donald

What is asking an honest question on a newsgroup if not research? And they didn't ask you for a circuit diagram, just a feel for if they are even in the ballpark. Nor did they ask you for a working circuit; evidently they will build and test, but it is no good building and testing if it is theoretically impossible to do the job.

THen what is the method used on automobiles and trucks to let them go through the tollbooth on the bridge at 40 miles an hour or so with the prepaid card stuck to the vehicle? This is not a leading question. I don't know what the method is, but it sure as little green apples isn't an inch or two. Gotta be a few feet at least.

So if you know of a method to achieve their goals, why not tell them (and the rest of us) rather than say why another method WON'T work?

Jim

snipped-for-privacy@gmail.com wrote in news:1186387567.138091.219910 @m37g2000prh.googlegroups.com:

My understanding is the RFID trasnciever "modules" simply output RS232 serial. That is fairly easy to trasnport and to a central computer.

You simply need an array of them to cover a larger area.

Passive RFID tags tend to have a range similar to the size of the antennas. 20m is not realistic.

The longest range passive RFID technology on the market is probably the ISO 15693 cards (check out Skidata for an application). They work at a range of 0.5-1.5m, with an antenna diameter of about

0.5m on the reader.

The tags are credit-card size, with the antenna coil along the edge.

To achieve the range you're talking about, look into active tags. they need a battery, but can achieve the 20m range and more.

Kind regards,

Iwo

Jim, Those tags aren't passive. They contain a battery and a detector that, when they are in the illuminated field, switch a dipole attenna in and out of resonance to change the reflection of the incoming RF.

Charlie

I'd like to thank everybody for their help. As this is our first time doing a design course as broad as this we started throwing ideas out on the internet before doing much real research. With 2 weeks of research - we have gone through several books including RFID primers, and the IBM sourcebook on RFID.

Thanks a tonne for the suggestion lwo - for the ISO 15693 RFID cards. The range is perfect and the readers are affordable for our design implementation.

We are more geared to using passive RFID as we'll need several and powering them on a broader scope would go against our design outcomes.

- Also the RFID is a small portion of the project and we are thus only interested in receiving a digital input from the RFID - in conjunction with a manual input by the user.

Thanks for all the help.

Right now our only issue is dealing with

1) programming an 8 bit binary number into the RFID ISO 15693 - i'll consult the faculty if they have the hardware to do this. 2) interpreting the signal from the RFID Module and sending it to our comparator circuit.

Does anyone have any technical RF module design book suggestions? We're down to 12 weeks to get the design done.

Thanks again for all the help.